TAMPA, Fla. (WFLA) — Officials at ZooTampa have released the cause of death for 12 stingrays that died at the zoo last month.

According to a statement released by the zoo Tuesday, a “supersaturation event” happened that caused gas embolisms, or gas bubble disease, in the rays.

“Gas bubble disease is a fatal condition that is similar to the ‘bends’ in human scuba divers which is caused by bubbles in the blood stream,” the statement said. “The event was not immediately known because the oxygen levels had resolved by the time the water was tested in the morning, following a standard water change.”

Zoo officials say they don’t know the exact cause of the supersaturation event but say it likely happened in the overnight hours.

“Possible causes include a system malfunction or a crack in portions of the pipe line which was not readily accessible,” a spokesperson said. “The Life Support System was checked daily and maintained by trained aquarists and maintenance staff on a schedule which followed the manufacturer’s recommendations and industry standards.”

Dr. Lawrence Killmar with ZooTampa says while it remains a mystery how the incident occurred, the future is crystal clear, they’re starting over.

“There’s no reason to take a chance, this is a living creature. We want to make sure we’re doing the best we can. We’re just going to start all over again,” Killmar said.

The 12 stingrays died on May 27 in the zoo’s Stingray Bay touch-pool habitat. The zoo later sent tissue and water samples to several labs, including one in Germany, to help figure out what happened.

Stingray Bay has been closed since the stingray deaths. The zoo announced Tuesday it will not reopen that habit.

“ZooTampa has decided that it will not reopen Stingray Bay, instead it will build an updated habitat, with a new water management system which will include redundancies, safeguards and updated procedures,” officials said.

Dr. Killmar tells 8 On Your Side, this system is 30 years old and it’s time for a new one.

“We just want to make sure we have the right system in place and it’s never 100 percent, but we’ll certainly mitigate those chances dramatically by starting all over again.” Killmar said “This was a tough day, it’s still a tough time for us. The staff invest their life into these animals, it’s hard on everyone, especially animal care staff.”

Zoo officals do not believe this was an act of malice or sabotage, sadly a system malfunction.